No tricks here, as fdew pointed out, this technique worked in the '70's too. Open differentials work better on slippery surfaces with added brake drag. I believe Dave Coleman claimed the Mazda does not use individual braking as part of their AWD traction control (individual braking is apparently only for dynamic stability). I am not sure why unless it's because it performs so well without it and they didn't want the extra load on the AWD differential. I really don't know, best guess is K.I.S.S.
Don't under-estimate the stock CX-5's snow/ice ability! I have made fresh tracks 10 miles into the backcountry in conditions I know would be challenging or impossible in most other 4x4's and AWD's and this year I drove a mile in even worse conditions up a slushy forest service road that stopped two guys in a Toyota 4x4 dead in their tracks. They made quite a mess where they were forced to turn around, the CX-5 motored right through, no problem! Whenever I go further than a mile or so I bring alpine-touring skis with me and full winter camping gear on-board in the event I can't drive out. Never had a problem though. The lightness of the CX-5 and the relatively high tire width/weight ratio is a big advantage in many conditions (although skinnier tires would be better for some conditions not requiring flotation).
Where the CX-5 is a stand-out is where it matters most to most people from a safety standpoint, at higher speeds on winter roads it just maintains directional control better. Less chance for that "oh s***!" slide moment into oncoming traffic and much better control if you need to drive around an oncoming vehicle sliding in your lane. This is a huge winter advantage and I'm sure the FWD models with appropriate tires would perform similarly.
